Cytotoxic and Apoptotic Effects of Novel Heterodinucleoside Phosphates Consisting of 5‐Fluorodeoxyuridine and Ara‐C in Human Cancer Cell Lines

In search for possible alternatives in the treatment of human malignancies we investigated several new heterodinucleoside phosphates containing of 5‐Fluorodeoxyuridine (5‐FdUrd) and Arabinofuranosylcytosine (Ara‐C). We show that all dimers tested inhibited the number of colonies of CCL228, CCL227, 5‐FU resistant CCL227 and HT‐29 human colon tumor cells with IC₅₀ values ranging from 0.65 to 1 nM. Dimer # 2 inhibited the number of sensitive and Ara‐C resistant H9 human lymphoma cells with IC₅₀ values ranging from 200 to 230 nM. Since no significant difference in the cytotoxicity of the dimers could be observed between sensitive and resistant cells, these compounds might be used in the treatment of 5‐FU and Ara‐C resistant tumors.